Question

Hydrogen in palladium is an example of:
A. Gas in gas
B. Gas in liquid
C. Liquid in solid
D. Gas in solid

Answer 1

Hint: The $$Pd-H$$ system is one of the best-known metal hydrogen systems. Pd has a simple face centered cubic structure, and can reversibly absorb and desorb hydrogen at ambient condition. The system has been extensively studied as a prototypical hydrogen storage system. When the H atom is absorbed into the Pd lattice, the Pd lattice expands due to the lattice adsorption around the H atom.

Complete step by step answer:
Palladium possesses to a remarkable extent the powder of absorbing or occluding hydrogen and numerous researches has been carried out by different investigators with a view to determining the condition of occluded gas, and the influence it has upon the properties of palladium.
At its melting point molten palladium absorbs less hydrogen than the solid metals, and consequently there is no spitting on solidification in an atmosphere of hydrogen.
The expression taken to represent that hydrogen molecules are in equilibrium with hydrogen atoms both in solution in the palladium and in the gaseous phase.
So, hydrogen is in gaseous form and palladium is an element which is in solid form.

Hence, option (D) is the correct answer.

Note: Here to note that hydrogen occluded by palladium though at first it appears to be represented by hydrogen. It appears to be monatomic and most recently concluded that hydrogen diffusing through palladium at high temperature is dissociated. Although in both cases higher temperatures than atmospheric are postulated.